The Collaborative International Dictionary of English v.0.48:

booklouse \book"louse`\ n. (Zool.)
   a minute wingless psocopterous insect (Liposcelis
   divinatorius) injurious to books and papers.

   Syn: book louse, deathwatch.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

booklouse
    n 1: minute wingless psocopterous insects injurious to books and
         papers [syn: booklouse, book louse, deathwatch,
         Liposcelis divinatorius]